\begin{gathered}\frac{8y-\sqrt{5} }{\sqrt{5}-y } =\frac{(8y-\sqrt{5} )(8y+\sqrt{5} )}{(\sqrt{5}- y)(8y+\sqrt{5} )} =\frac{64y^{2}-5 }{(\sqrt{5}- y)(8y+\sqrt{5} ) } \\ \\ \\ \frac{3\sqrt{a}-1 }{\sqrt{3}+a }=\frac{{(3\sqrt{a}-1 )(3\sqrt{a}+1 )}}{(\sqrt{3}+a )(3\sqrt{a}+1)}}  =\frac{9a-1}{(\sqrt{3}+a )(3\sqrt{a}+1)} \\ \\ \\ \frac{\sqrt{7} }{\sqrt{7}+\sqrt{2}  }=\frac{\sqrt{7}*\sqrt{7}  }{\sqrt{7}(\sqrt{7} +\sqrt{2})} =\frac{7}{7+\sqrt{14} }\end{gathered}​

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